In the North Carolina follow up study of puberty, height of boys at puberty increased with transplacental exposure to DDE, as did weight adjusted for height. Lactational exposure to DDE had no apparent effects; neither did transplacental or lactational exposure to PCBs. There was no effect on the ages at which pubertal states in boys were attained. There was some tendency for girls with higher transplacental PCB or DDE exposure to mature earlier, but the differences were not significant. Girls with the highest transplacental PCB exposures were heavier for their heights than other girls by 5.4 kg, but differences were significant only if the analysis was restricted to white girls. In Taiwan in 1979, more than 2000 people were poisoned by heat-degraded PCBs. We have shown that, after 13 years of follow-up, the survivors have an increase in mortality from non-malignant liver disease; however, they do not yet show an excess of liver cancer, which is occurring in survivors of a similar poisoning in Japan in 1969. We continue to follow this cohort, including the children born to poisoned mothers. In Taiwan, we are beginning design of a clinical and endocrinological study of peri-pubertal girls who were in utero when their mothers were poisoned by PCBs/PCDFs